Automatic test equipment (ATE) plays an important role in the manufacture of semiconductor devices. The equipment typically applies test signals to one or more semiconductor devices under test (DUTs) and detects responsive output signals. By comparing the values of the detected signals to expected values, the acceptable functionality of the device can be confirmed.
With reference to FIG. 1, conventional ATE often includes a mainframe rack or computer workstation 10 that serves as a test controller for a separately disposed test head 12. The test head typically houses the pin electronics or “channel cards” that interface the ATE channel circuitry to the DUT pins (not shown) via a device-interface-board (DIB) 14. The tester channel resources usually follow a one-to-one correspondence with the DUT pins.
To maintain optimum accuracy, predictability and repeatability, the ATE channels are regularly calibrated and validated. This is commonly carried out by measuring signals along the ATE channel paths and determining whether the detected signals fall within predefined performance specifications. The measurement data is typically collected through use of an automated robot 16 that positions an electrical probe assembly 18 sequentially through a plurality of test points 20 disposed on the device-interface-board 14. The test points are located on the “channel” paths between each pin of the DUT and the tester.
Conventional calibration/validation robots often employ test probe assemblies that mount rigidly to the robot 16 through use of a fastener. While this is an inexpensive way to effect mounting of the probe, it is susceptible to damage if the probe inadvertently comes into contact with an unexpected surface. Repairing and replacing a rigidly mounted probe can result in an undesirable delay in validating the tester channels, causing an increase in overall test costs. Moreover, a rigidly mounted probe may loosen over several hundred touchdowns, possibly compromising the accuracy of the probe-to-test point registration and/or signal fidelity associated with the probe assembly.
What is needed and currently unavailable is a calibration/validation probe assembly mounting scheme for automatic test equipment that minimizes cost while maximizing calibration/validation accuracy. The high fidelity electrical probe assembly of the present invention satisfies these needs.